This invention relates to liquid-vapour contact apparatus suitable for use in fractionally distilling a liquid mixture comprising two or more components.
Conventional distillation columns for use in separating air employ circular or part-circular liquid-vapour contact trays. It has been found that aboard ship such columns perform badly as a result of the motion of the ship causing maldistribution of the liquid on the trays. Our UK patent specification No. 1 478 459 relates to a distillation column whose trays are each provided with spaced vertical baffles that limit displacement of the liquid across the tray in a direction normal to that of the liquid flow. The aforesaid UK patent specification describes an embodiment of such a column in which trays with generally rectangular liquid-bearing surfaces are employed. However, it has been found necessary to employ generally tubular column walls as difficulties arise in fabricating a vessel (for containing the trays) in the shape of a cuboid. Moreover, when a cylindrical vessel is employed it is found necessary to use separate reboilers and condensers. These requirements tend to add unnecessarily to the overall size of the apparatus thereby giving rise to further disadvantage since on board ship there is generally limited space available for an air separation column. The invention aims at providing a liquid-vapour contact apparatus that can for example be fabricated by vacuum brazing and that has vertical outer walls disposed in the manner of the vertical faces of a cuboid.